Fuel injector nozzles

ABSTRACT

An injector nozzle has a body having a nozzle through which fuel is delivered. The nozzle includes a port having an internal surface and a valve member having a complementary external surface. The valve member is movable relative to the port to respectively provide a passage between the surfaces for delivery of fuel in the form of a spray or sealed contact therebetween to prevent the delivery of fluid. A fluid flow control body is located beyond an extremity of the nozzle body corresponding to the location of the port. The control body has a control surface configured and positioned such that the fuel spray established by fluid issuing from the port will follow a path determined at least in part by that control surface. The flow control body is in part hollow.

This invention relates to a valve controlled nozzle for the injection offluid, such as a valve controlled nozzle for the injection of fuel in aninternal combustion engine. In this specification, the term "internalcombustion engine" is to be understood to include engines having anintermittent combustion cycle such as reciprocating or rotary enginesoperating on either the two or four stroke cycle.

The characteristics of the fuel spray delivered from an injector nozzleto an internal combustion engine, such as directly into the combustionchamber, have a major effect on the control of the combustion of thefuel, which in turn affects the stability of the operation of theengine, the engine fuel efficiency and the composition of the engineexhaust gases. To optimise these effects, particularly in a sparkignited engine, the desirable characteristics of the fuel spray issuingfrom the injector nozzle include small fuel droplet size (liquid fuels),controlled spray geometry and in the case of direct injected engines,controlled penetration of the fuel into the combustion chamber. Further,at least at low fuelling rates, a relatively contained and evenlydistributed ignitable cloud of fuel vapour in the vicinity of the enginespark plug is desirable.

Some known injector nozzles, used for the delivery of fuel directly intothe combustion chamber of an engine, are of the outwardly opening poppetvalve type, which deliver the fuel in the form of a cylindrical ordivergent conical spray. The nature of the shape of the fuel spray isdependent on a number of factors including the geometry of the port andvalve constituting the nozzle, especially the surfaces of the port andvalve immediately adjacent the valve seat, where the port and valveengage to seal when the nozzle is closed. Once a nozzle geometry hasbeen selected to give the required performance of the injector nozzleand hence the combustion process, it is important to maintain suchgeometry otherwise the performance of the engine can be impaired,particularly at low fuelling rates.

The attachment or build-up of solid combustion products or otherdeposits on the nozzle surfaces over which fuel flows can affect thegeometry of the fuel flow path through the open nozzle and can thereforeaffect the creation of the correct fuel distribution, and hence thecombustion process of the engine. The principal cause of build-up onthese surfaces is the adhesion thereto of carbon particles or otherparticles that arise from the combustion of the fuel, includingincomplete combustion of residual fuel left on these surfaces betweeninjection cycles. Methods of reducing or controlling such build-up areknown as disclosed in the applicant's Australian Patent Application Nos.36205/89 and 71474/91.

It is known that a hollow spray or fuel plume issuing from a nozzleinitially follows a path principally determined by the exit directionand exit velocity of the fuel. It is also known that as the fuel sprayadvances beyond the delivery end of the injector nozzle, a pressure iscreated within the area bound by the spray immediately downstream of thenozzle that is lower than the pressure on the outside of fuel spray andwhich promotes an inward contraction of the spray. This is referred toas "necking".

It has been found that disturbances to the fuel flow issuing from aninjector nozzle can significantly influence the shape of the fuel sprayor plume, particularly during and subsequent to the necking thereof.Such influences can promote unpredictable deflection and/or dispersionof the fuel, which in turn can adversely affect the combustion processand thus may give rise to an increase in fuel consumption, undesirablelevels of exhaust emissions, and also instability in engine operation,particularly during low load operation.

Disturbances that can give rise to such undesirable influences includethe presence of irregular deposits on the surfaces defining the injectornozzle exit, such as carbon and other combustion related deposits,eccentricity of the valve and seat components of the nozzle, and orexcessive clearance between the stem supporting the valve and the borein which the valve stem axially moves as the valve opens and closes theinjector nozzle exit. Lateral movement or eccentricity of the valve, anddeposits on the surfaces of the valve or valve seat can each result inchanges in the relative rate of flow through different sections of theperiphery of the nozzle, thus causing an asymmetric fuel spray.

The above discussed disturbances to the delivery of fuel, such as to thecombustion chamber of an engine, are particularly significant in enginesoperating with a highly stratified air/fuel mixture, such as isrecognised as highly desirable to control exhaust emissions during lowload operation.

The applicant's U.S. Pat. No. 5,551,638 provides an injector nozzle witha projection dependent from the valve head thereof and having anexternal toroidal surface. However, a projection having such geometryhas been found by the applicant to be only one of a number of differentgeometries which it has developed and found suitable in the control ofthe shape and direction of the fuel spray or plume issuing from aninjector nozzle. Furthermore, the applicant has found that theprojections as disclosed in the aforesaid co-pending patent applicationmay be improved from the point of view of heat transfer and mechanicalperformance so that the projections have a greater heat retention andcapacity to combust, or otherwise remove, carbon deposits therefrom. Theapplicant has also discovered in their research different arrangementsfor the support of the projection which are advantageous from the pointof view of the control of the shape and direction of the fuel sprayissuing from an injector nozzle.

The present invention therefore provides, in its broadest form, aninjector nozzle comprising a body having a nozzle through which fluid isdelivered, said nozzle comprising a port having an internal surface anda valve member having a complementary external surface, said valvemember being movable relative to the port to respectively provide apassage between said surfaces for the delivery of fluid in the form of aspray or sealed contact therebetween to prevent the delivery of fluid,characterised by the provision of a fluid flow control body locatedbeyond an extremity of the body of the injector nozzle corresponding tothe location of the port, said flow control body having a controlsurface spaced from the nozzle in the direction of movement of the valvemember, said control surface being configured and positioned to promotethe fluid spray established by the fluid issuing from the port to followa path determined by the shape of said control surface.

Preferably the flow control body is configured and positioned to promotethe fuel spray to contract inwardly to follow the path determined by theshape of the control surface.

Conveniently, the flow control body may be mounted to either the valvemember or the body of the injector nozzle to extend beyond the extremitythereof in a direction generally corresponding to the direction that thefluid spray issues from the port. However, such location or mounting isnot essential and any advantageous location or mounting may be employed.

The present invention may be advantageously applied to a fuel injectornozzle as used in an internal combustion engine, and particularly, afuel injector nozzle delivering fuel directly into the combustionchamber of the engine, and particularly where the fuel is entrained in agas such as air. Accordingly, the flow control body may beadvantageously located at specific locations within the enginecombustion chamber. Where it is desired to guide the fuel spray in aparticular direction within the combustion chamber of an internalcombustion engine, for example, towards an igniting means such as aspark plug, it may be desirable to mount the flow control body elsewherethan on the valve member. Hence, the flow control body is notnecessarily a projection or portion provided at one end of the valvemember. For instance, the flow control body may be dependant from thecylinder head, cylinder wall, spark plug or any other appropriatesurface.

The control surface of the flow control body may typically be anexternal surface and the flow control body may be hollow, but for otherapplications, an internal control surface may be more appropriate.

Conveniently, in the case of a flow control body connected to the valvemember or the body of the injector nozzle, the flow control body may beconfigured to be at least partly hollow so as to provide greater heatretention properties due to a reduced conductive flow path through whichheat can pass to the valve member and/or nozzle. Thus, high temperaturesare more effectively maintained in the flow control body and hence,problems arising from carbon deposition on the surfaces of the nozzleand/or valve member are likely to be less significant. Further, in thecase of a flow control body connected to a moving valve element, thereduced weight results in a more responsive valve mechanism. Stillfurther, the hollow construction employed in the configuration of theflow control body may extend into the valve member itself, thus reducingthe impact momentum upon opening and closing movement of the valvemember. In particular, where the flow control body includes a neckedportion dependent from the valve head, the hollow portion would alsoserve to create a restricted heat conduction path to the valve memberand hence the nozzle.

The flow control body may be of a wide variety of geometric shapes bothin cross-section and lengthwise, including assymetric cross-sections ora cross-section of constant geometry but varying cross-sectional area.Further, the flow control body may be provided with internal or externalgrooves that may assist in the shaping of a desired spray geometry. Suchgrooves, may also provide an increased surface area of the flow controlbody which may be useful in achieving greater heating of the flowcontrol body. Further, the flow control body does not necessarily haveto be axially aligned with the valve member or the direction of movementthereof, nor does it have to be symmetric about a particular axis.

Further, the flow control body may be provided with a portion which ismovable in relation to the remainder thereof. For example, a movableportion can be attached to a flow control body that is connected to thevalve member. The movable portion can take the form of a collar movablymounted upon a spigot fixed to the valve member, the collar beingmovable in response to the movement of the valve member. The movement ofthe movable portion may be constrained by the provision of impact faceswith which the movable portion collides causing vibration of the flowcontrol body to promote dislodgement of any carbon deposits thereon.Preferably, the surface that functions to guide the fluid spray isprovided either entirely or partly on the movable portion.

In each of these proposals, the flow control body is preferablyconfigured and positioned such that the fluid spray, issuing from thenozzle when open will embrace a portion of the control surface of theflow control body adjacent the valve member and subsequently flow alonga path at least partly determined by the shape or form of the flowcontrol surface. Furthermore, the flow control body can be employed invalves of the poppet or pintle type and can be attached to the valvemember of either of such valve types.

Conveniently, the spacing of the flow control body when it extends fromthe valve member, can be achieved by providing a necked portion betweenthe valve member and the adjacent end of the flow control body whichreduces the cross-sectional area through which heat can flow from theflow control body into the valve member and hence be dissipated throughthe injector nozzle to the engine cylinder or cylinder head. Thisnecking contributes to retaining heat in the flow control body tothereby maintain the control body at a sufficiently high temperature toburn off any carbon or other particles that develop or are deposited onthe surface thereof. Equally, where the flow control body depends fromthe body of the injector nozzle or another part of the combustionchamber rather than the valve member, a necked or narrow portion can beprovided to achieve the heat retention effect described above.

The use of the flow control body to aid in the control of theconfiguration and path of the fluid spray, created as fluid issues fromthe injector nozzle, significantly contributes to better management ofthe combustion process and hence, better control of exhaust emissionsand engine fuel efficiency. The flow control body stabilises the fluidspray by providing a physical surface to guide the spray downstream ofthe nozzle. This has the result of reducing lateral deflection of thefluid during the injection period.

The engagement of the fluid spray with the control surface of the flowcontrol body arises in the main from the natural inward necking of thespray a short distance after the spray issues from the injector nozzlepartly due to a phenomenen known as the Coanda effect. Once suchengagement has been established, the spray will maintain proximity with,and be guided by, the control surface of the flow control body. Thespray will thus follow a path generally corresponding with the adjacentsurface of the flow control body thereby reducing the possibility oflateral displacement and/or disturbance of the fluid spray.

It is to be appreciated that the guidance of the fluid spray, by thecontrol surface of the flow control body will promote uniformity in thedirection of flow of the fluid spray into the engine combustion chamber,countering other influences as previously discussed that could causeirregularities or diversion of the fluid spray or portions thereof. Theguidance of the fluid spray can also aid in the correction ofdifferences in or disturbances to the spray arising from manufacturingvariations including tolerance variations from engine to engine.

The invention will be more readily understood from the followingdescription of several practical but exemplary arrangements of the fuelinjector nozzle as depicted in the accompanying drawings.

In the drawings:

FIG. 1 is a part-sectional view of a fuel injector valve havingdependent therefrom a flow control body according to a first embodimentof the present invention;

FIG. 2 is a part-sectional view similar to FIG. 1 of another form of theflow control body;

FIG. 3 is a part-sectional view of a fuel injector valve having afurther alternative form of flow control body dependent therefrom;

FIG. 4 is a part-sectional view similar to FIG. 3 of another form of theflow control body;

FIG. 5 is a part-sectional view of a fuel injector valve havingdependent therefrom a multi-part flow control body;

FIG. 6 is a part-sectional view of a fuel injection nozzle having a flowcontrol body supported from the injector body thereof; and

FIG. 7 is a part-sectional view of a fuel injection nozzle having a flowcontrol body supported from the injector body thereof to direct fueltowards a spark plug.

The fuel injector nozzles and valves as depicted in FIGS. 1 to 7 andhereinafter described, can be incorporated into a wide range of fuelinjectors used for the delivery of fuel into the combustion chamber ofan engine. Typical forms of injectors in which the nozzle ashereinbefore described can be incorporated are disclosed in theapplicant's U.S. Pat. No. 4,934,329 and in U.S. Pat. No. 4,844,339 andthe disclosure of each of these prior documents is hereby incorporatedin this specification by reference.

Referring now to FIG. 1 of the drawings, the body 10 of the fuelinjector nozzle is of a generally cylindrical shape having a spigotportion 11 which is arranged to be received in a bore provided in aco-operating portion of a complete fuel injector unit. A valve member 13arranged to co-operate with the nozzle body 10 has a valve head 14 and avalve stem 15. The stem 15 has a guide portion 18 which is axiallyslidable in a bore 12 of the body 10. The stem 15 is hollow so that thefuel can be delivered therethrough, and openings 16 are provided in thewall of the stem 15 to permit the fuel to pass from the interior of thestem 15 into the bore 12.

The valve head 14 is of a part-spherical form and is received in a port17 provided in an end of the body 10 which communicates with the bore12. The wall of the port 17 is of a frustro-conical form and engages thevalve head 14 along the seat line 20 when the valve 13 is in the closedposition. A flow control body 30 is formed integral with the head 14 ofthe valve 13 and is connected thereto by a neck portion 31, which is ofa substantially reduced cross-sectional area compared to the majority ofthe flow control body 30 so as to restrict heat flow from the flowcontrol body 30 into the valve 13 and injector body and thereby raisethe temperature of the flow control body 30 as previously referred toherein.

The flow control body 30 is comprised of two portions, 36 and 37 both ofa truncated conical shape with the shorter portion 36 adjoining the neckportion 31. In order to further restrict the heat flow from the flowcontrol body 30 to the nozzle, a cylindrical cavity 30b is formed withinthe guide projection 30. Accordingly, the remaining wall thickness orheat transfer area of the flow control body 30 is significantly lessthan would be available if the flow control body 30 were of a solidconstruction. Thus there is created a restriction to heat transfer tothe injector nozzle in the vicinity of 30a and improved heat retentionin the flow control body 30.

It is to be noted that the cavity 30b need not be cylindrical as anygeometry of the cavity 30b which reduces the heat conduction path may beemployed. As an additional benefit, the provision of cavity 30b willreduce the momentum and hence impact speed of the valve member 13 onclosing thus improving injection control and noise reductioncharacteristics.

The diameter of the junction 32 between the two portions 36 and 37 ofthe flow control body 30 is selected so that the fuel spray issuing fromthe port 17 when open, will follow a path based on an external surface33 of the flow control body 30. The diameter of the junction 32 topromote attachment of the inner boundary layer of the issuing fuel sprayto the external surface 33 of the low control body 30 so that the fuelspray will follow a path complementary to surface 33 is largelydetermined experimentally. The configuration of the external surface 33may be selected to specifically direct the fuel in a desired directionnot co-axial with the injector nozzle.

If the configuration of the port 17 and valve head 14 provide a fuelspray that diverges outwardly from the nozzle end face, it may bedesirable to have the diameter of the flow control body 30 at thejunction 32 thereof larger than the diameter of the valve head 14.However, the diameter at the junction 32 must not be such to extend intoor through the fuel spray issuing from the nozzle, as this would resultin a breaking up and/or an outward deflection of the fuel spray contraryto the aim of the invention. Further, the diameter of the fuel controlbody 30 adjacent the nozzle may be less than that of the valve head 14,as an issuing fuel spray naturally collapses inwardly after leaving thenozzle, as previously referred to, and would be thus brought intocontact with the external surface 33 of the flow control body 30.Further, the axial spacing between the end face of the valve head 14 andthe commencement of the external surface 33 at the junction 32 of theflow control body 30 is selected to promote the attachment of theissuing spray to the external surface 33.

It will be appreciated by those skilled in the art that the dimensionsof the flow control body 30 are influenced by a number of factorsincluding the dimensions of the injector nozzle, the nature of the fluidor fuel to be injected and the velocity and direction of delivery fromthe nozzle. Typical dimensions of the flow control body 30 as shown inFIG. 1 are provided below by way of example only:

    ______________________________________                                        Diameter of the Sphere Defining                                                                         5.5 mm                                              the Convex Valve Surface                                                      Valve Seat Included Angle                                                                              80°                                           Flow Control Body End Diameter                                                                          2.5 mm                                              Flow Control Body Lower Included Angle                                                                 40°                                           Flow Control Body Upper Included Angle                                                                 85°                                           Flow Control Body Length  8.2 mm                                              ______________________________________                                    

There is shown in FIG. 2 an alternative form of injector nozzle and flowcontrol body wherein a guide surface 27 of the flow control body 26 isnot of a truncated conical form, but is of a tapered form curved in thelongitudinal direction. Initially the surface 27 is of a non-convergentform in an upper portion 29 and smoothly translates to a convergent formin a lower portion 28 remote from a valve head 23.

It is to be noted that as the surface of the valve head 23 and thesurface of a co-operating port 25 are substantially co-axial andterminate at the delivery end of the nozzle substantially at a commondiametric plane, the fuel spray or plume issuing therefrom willinitially contact the diverging portion 29 of the surface 27 and willsubsequently follow a path determined by the converging portion 28 ofthe surface 27 towards the lower end of the flow control body 26. Inaddition, a plurality of arcuate shaped longitudinal grooves 41 may beprovided on the projection 26 as hereinbefore described. Any desirednumber or geometry of grooves 41 may be provided.

As shown in FIGS. 3 and 4, triangular and rectangular prismatic shapedflow control bodies 42 or 43, respectively, may be provided dependentfrom the valve member 13 of the nozzle. It will be noted that the flowcontrol bodies 42, 43 have a constant prismatic surface in the axialdirection of the valve 13. Further, the geometry of the flow controlbodies 42, 43 is shown in FIGS. 3 and 4 respectively as beingsymmetrical about the axis of the valve 13, but it is not essential thatthey be symmetrical or axially aligned.

Referring now to FIG. 5, there is shown a construction in which a flowcontrol body 35 is in the form of a spigot 38 projecting centrally froman end face 48 of a valve head 39 in the downstream direction,terminating in a flange portion 47, and having a movable toroidal collar50 located on the spigot 38 between the valve head 39 and the flangeportion 47. The external surface 50a of the collar 50 provides the flowcontrol surface to which the fuel spray or plume will attach to and beguided on a prescribed path as previously discussed.

The collar 50 has a substantial degree of freedom to move in the axialdirection of the spigot 38, and will so move in response to themovements of the valve head 39 to open and close a co-operating port ofthe injector nozzle. When this movement occurs, impact of the collar 50will either occur at flange 47 or end face 48 of the valve head 39. Theimpact of the collar 50 causes vibration of the entire flow control body35 which is sufficient to promote dislodgment of carbon depositsthereon.

As modifications to the embodiment of FIG. 5, there may be provided ahollow form of spigot 38 and/or flange 47 to maximise heat retention inthe flow control body 35. Also, movable components of different geometryto that of the toroidal collar 50 may be used. In addition, the collar50, spigot 38 and flange 47 may be constructed of materials of differentthermal conductivity or density in order to change the heat retention orvibrational characteristics of the flow control body 35.

In regard to each of the embodiments described hereinbefore, the flowcontrol body can be constructed of a low heat transfer material,particularly a material having a lower heat transfer rate than thestainless steel normally used for the valve of a fuel injector nozzle.

FIG. 6 shows a construction in which a flow control body 61 is arrangedat the downstream extremity of an arm 60 extending from an end face 70of the spigot portion 11 as previously described in FIG. 1. The arm 60is designed such as not to occlude the issue of fuel from the port 17,but such as to ensure that the fuel spray issuing from the nozzle whenopen will follow a path based on the external surface 61a of the flowcontrol body 61. If desired, the arm 60 may be constructed of a higherthermal conductivity material than that of the spigot portion 11 suchthat heat transfer to the flow control body 61 and heat retentiontherein is promoted.

Referring now to FIG. 7, at the downstream end of an arcuate arm 160,there is located a flow control body 161 having the axis thereof at anangle to the central axis of a valve member 113 and providing a controlsurface 173. In use, a plume or spray of fuel issuing from the port 117will be guided in the direction of a spark plug 180 along the controlsurface 173.

It is to be understood that the flow control body 61, 161 described andas shown in FIGS. 6 or 7 may be connected either to the valve member,the nozzle body itself, the spark plug, the cylinder wall, or, indeed,any advantageous location in the cylinder head. The location is not alimitation upon the present invention. Furthermore, the flow controlbody 61, 161 need not be symmetrical in any particular way and may beprovided with a hollow portion as referred to hereinbefore.

The present invention is applicable to poppet type fuel injector nozzlesof all constructions where the fuel issues therefrom in the form of aplume including injectors where fuel alone is injected and where fuelentrained in a gas, such as air, is injected. Examples of specificnozzle constructions to which the invention can be applied are disclosedin the applicant's U.S. Pat. Nos. 5,090,625 and 5,593,095 both beingincorporated herein by reference. Also, the injector nozzles asdisclosed herein can be used for injecting other fluids in addition tofuel with similar beneficial control of the fluid spray. Furthermore,the injector nozzle of the invention may equally be used in valves ofthe pintle type.

The invention is not to be limited by the foregoing description andother variations may be developed by those skilled in the art which fallwithin the scope of the invention. It is to be understood that thepresent invention may be applied to injector nozzles supplying fueldirectly into the combustion chamber or into the engine air supplysystem, and may be applied to both two and four stroke cycle engines. Inaddition, the injector nozzles may be used in applications other thanthe delivery of fuel to internal combustion engines.

I claim:
 1. An injector nozzle comprising a control body having a nozzlethrough which fluid is delivered, said nozzle comprising a port havingan internal surface and a valve member having a complementary externalsurface, said valve member being movable relative to the port torespectively provide a passage between said surfaces for the delivery offluid in the form of a spray or sealed contact therebetween to preventthe delivery of fluid, a fluid flow control body located beyond anextremity of the body of the injector nozzle corresponding to thelocation of the port, said flow control body having a control surfacespaced from the nozzle in the direction of movement of the valve member,said control surface being configured and positioned to promote thefluid spray established by the fluid issuing from the port to follow apath determined by the shape of said control surface, wherein the flowcontrol body is in part hollow.
 2. An injector nozzle as claimed inclaim 1, wherein the flow control body is supported by a neck portionextending between the valve member and the flow control body to therebydefine an annular space between the flow control body and the valvemember that extends substantially to the periphery of the valve member.3. An injector nozzle as claimed in claim 1 wherein the flow controlbody is supported by a member rigidly secured to a portion of the nozzlebody.
 4. An injector nozzle as claimed in claim 1, wherein the flowcontrol body is positioned and configured to promote the fluid spray tocontract inwardly to follow said path.
 5. An injector nozzle as claimedin claim 1, wherein the control surface is assymetrical with respect tothe common axis of the port and valve member.
 6. An injector nozzle asclaimed claim 1, wherein the control surface is symmetrical with respectto an axis inclined to the common axis of the port and valve member. 7.An injector nozzle as claimed in claim 1, wherein the flow control bodyis open at an end thereof furthermost from the valve member and a cavityextends from said end towards the opposite end of the flow control body.8. An injector nozzle as claimed in claim 1, wherein the flow controlbody is mounted on a core member fixedly mounted on the valve member,said flow control body having limited free movement on the core in theaxial direction thereof.
 9. An injector nozzle as claimed in claim 1,wherein the flow control body is of substantially circular cross-sectionthroughout the length thereof, and progressively increases in diameterfrom the end thereof remote from the valve member to an intermediatediametric plane and progressively decreases in diameter from saidintermediate diametric plane toward the other end of the flow controlbody.
 10. An injector nozzle as claimed in claim 9, wherein the axis ofthe flow control body is inclined to the axis of the valve member andport.